During the past several decades, there has been a nearly constant exponential growth in the capabilities of silicon-based microelectronics. The prediction by Gordon E. Moore, the co-founder of Intel Corporation, that the number of transistors that could be fit on a computer chip would double every 18 months has proved true, and there has been a dramatic decrease in the size of electronic elements. However, it is unlikely that these advances will continue much into the next decade due to fundamental physical limitations which prevent current designs from functioning reliably at a nanometer scale, as well as economic limitations such as high fabrication costs.
Recently, nanotechnology has gained tremendous attention because of its potential to overcome the limitations of silicon-based technology. For example, various nano-scale devices based on carbon nanotubes and/or nanowires, which have interesting electrical and/or optical properties, have been developed. In addition, nanoelectronic devices, such as PN diodes and light emitting diodes, based on cross-structures of nanostructures, such as carbon nanotubes and nanowires, have been reported. However, it is extremely difficult to mass-produce cross-structures of nanostructures.